The present invention provides covert features to aid in the security or authentication of objects. The features can be conveyed through ink or dye which appear invisible (or at least generally imperceptible) to a human viewer under normal or ambient lighting conditions. The ink or dye fluoresces or become visibly perceptible by a human viewer under non-visible lighting conditions like ultraviolet (UV) and infrared (IR).
Some of these inks or dyes are designed to fluoresce, after non-visible light illumination, according to a predetermined decay rate. That is to say that inks and dyes can be designed to have different emission decay rate characteristics. When two or more of such predictably decaying inks are used in concert, the security or authentication of an object is greatly enhanced as taught herein.
For the purposes of this disclosure, identification documents are broadly defined and may include, e.g., credit cards, bank cards, phone cards, passports, driver's licenses, network access cards, employee badges, debit cards, security cards, visas, immigration documentation, national ID cards, citizenship cards, social security cards, security badges, certificates, identification cards or documents, voter registration cards, police ID cards, border crossing cards, legal instruments or documentation, security clearance badges and cards, gun permits, gift certificates or cards, labels or product packaging, membership cards or badges, etc., etc. Also, the terms “document,” “card,” and “documentation” are used interchangeably throughout this patent document. Identification documents are also sometimes referred to as “ID documents.”
Identification documents can include information such as a photographic image, a bar code (e.g., which may contain information specific to a person whose image appears in the photographic image, and/or information that is the same from ID document to ID document), variable personal information (e.g., such as an address, signature, and/or birth date, biometric information associated with the person whose image appears in the photographic image, e.g., a fingerprint), a magnetic stripe (which, for example, can be on a side of the ID document that is opposite a side with a photographic image), and various designs (e.g., a security pattern like a printed pattern including a tightly printed pattern of finely divided printed and unprinted areas in close proximity to each other, such as a fine-line printed security pattern as is used in the printing of banknote paper, stock certificates, and the like). Of course, an identification document can include more or less of these types of features.
One exemplary ID document comprises a core layer (which can be pre-printed), such as a light-colored, opaque material, e.g., TESLIN, which is available from PPG Industries) or polyvinyl chloride (PVC) material. The core can be laminated with a transparent material, such as clear PVC to form a so-called “card blank”. Information, such as variable personal information (e.g., photographic information, address, name, document number, etc.), is printed on the card blank using a method such as Dye Diffusion Thermal Transfer (“D2T2”) printing (e.g., as described in commonly assigned U.S. Pat. No. 6,066,594, which is herein incorporated by reference), laser or inkjet printing, offset printing, etc. The information can, for example, include an indicium or indicia, such as the invariant or nonvarying information common to a large number of identification documents, for example the name and logo of the organization issuing the documents.
To protect the information that is printed, an additional layer of transparent overlaminate can be coupled to the card blank and printed information, as is known by those skilled in the art. Illustrative examples of usable materials for overlaminates include biaxially oriented polyester or other optically clear durable plastic film.
One type of identification document 100 is illustrated with reference to FIG. 1. The identification document 100 includes a security feature 102. The security feature 102 can be printed or otherwise provided on a substrate/core 120 or perhaps on a protective or decorative overlaminate 112 or 112′. The security feature need not be provided on the “front” of the identification document 100 as illustrated, but can alternatively be provided on a backside of the identification document 100. The identification document 100 optionally includes a variety of other features like a photograph 104, ghost or faint image 106, signature 108, fixed information 110 (e.g., information which is generally the same from ID document to ID document), other machine-readable information (e.g., bar codes, 2D bar codes, optical memory) 114, variable information (e.g., information which generally varies from document to document, like bearer's name, address, document number) 116, etc. The document 100 may also include overprinting (e.g., DOB over image 106) or microprinting (not shown).
Of course, there are many other physical structures/materials and other features that can be suitably interchanged for use with the identification documents described herein. The inventive techniques disclosed in this patent document will similarly benefit these other documents as well.
According to one aspect of the present invention, an identification document includes at least one of a photographic representation of a bearer of the identification document and indicia provided on the identification document. The identification document further includes a security feature. The security feature has: i) a first set of elements provided on a surface of the identification document by a first ink, the first ink including a first emission decay rate; and ii) a second set of elements provided on the surface of the identification document by a second ink, the second ink including a second emission decay rate. The first emission decay rate is relatively shorter than the second emission decay rate. And the first set of elements and second set of elements are arranged on the surface of the identification document so as to collectively convey a first pattern when a first non-visible light excites the first ink and the second ink. The second set of elements conveys a second pattern that becomes distinguishable as emissions from the first ink decay, but before emissions from the second ink are extinguished.
Another aspect of the present invention is a method to detect a security feature provided on an identification document. The security feature includes a first set of elements printed on a surface of the identification document with first ink and a second set of elements printed on the surface of the identification document with second ink. The second ink includes an emission decay time that is longer than an emission decay time of the first ink. The method includes the steps of: i) exciting the first ink and the second ink; and ii) observing at least a predetermined characteristic of the security feature after emissions from the first ink fall to a first level and before emissions from the second ink fall to a second level.
Still another aspect of the present invention is a method of providing a security feature for a physical object. The method includes: i) arranging a first set of elements on a surface of the physical object via a first ink, the first ink comprising a first emission decay rate; and ii) arranging a second set of elements on a surface of the physical object via a second ink, the second ink comprising a second emission decay rate. The second emission decay rate is relatively longer than the first emission decay rate. The first set of elements are arranged so as to cooperate with the second set of elements to convey a first pattern through emissions of the first ink and the second ink, and the second set of elements are arranged so as convey a second pattern which becomes distinguishable after emissions from the first ink reach a first level but before emissions from the second ink are extinguished.
The foregoing and other features, aspects and advantages of the present invention will be even more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.